This invention relates to fluid brake control systems for railroad trains and it more particularly relates to modifications of service valves to perform the function of continuous quick service.
The ABD control valve device, which is generally disclosed in the Wilson U.S. Pat. No. 3,232,678 is generally known in the art as a control valve device having a service slide valve providing for a first stage of quick service, known as preliminary quick service, together with a second stage of quick service, when the service valve moves to service position for charging a brake cylinder, or brake motor, from a brake pipe to a predetermined initial pressure, which is generally 10 lbs.. The ABD control valve device has been further improved to provide a third stage of quick service known as continuous quick service by adding an accelerated application diaphragm piston valve as disclosed in the Wilson U.S. Pat. No. 3,175,276, that is controlled by an emergency control slide valve. Such a modified ABD control valve device is currently in use and is generally known as an ABDW control valve device.
An object of the present invention is to provide a fluid brake control system which substantially obviates one or more of the limitations and disadvantages of the described prior art systems.
Another object of the present invention is to incorporate a third stage of quick service in the service slide valve, thus eliminating the need for the accelerated application diaphragm piston valve of current ABDW valves.
Another object of the present invention is to reduce costs by reducing the number of separate valves required in an ABDW control valve device.
Other objects, purposes and characteristic features the present invention will be in part obvious from the accompanied drawings and in part pointed out as the description of the invention progresses.